Magneto excited condenser discharge ignition system

ABSTRACT

A dynamoelectric generating device for internal combustion engines combining a breakerless ignition system of a condenser discharge type with an alternator for generating electrical power wherein the energizing and timing coils for the ignition system are mounted on a stator with the power generating coils, both being excited by a rotating permanent magnet structure driven by the engine. An automatic spark advance is provided actuated at a predetermined engine speed.

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[54] MAGNIETO EXCITED CONDENSER DISCHARGE IGNITION SYSTEM [72] Inventor:Ray C. Noddin, Chicopee, Mass.

[73] Assignee: lEltra Corporation, Toledo, Ohio [22] Filed: July 6, 1970211 Appl. No.: 52,429

[52] U.S.Cl. ..l23/l49A,123/149C [51] lint. Cl ..F02p l/00 [58] FieldoiSearch ..l23/l48 E, 149 R, 149D [56] References Cited UNITED STATESPATENTS 3,358,665 12/1967 Carmichael et a]. ..l23/l48 E 3,495,579 2/1970Davalillo ..l23/149 3,465,739 7/1969 Burson ..l23/148 E X 3,464,3977/1969 Burson l23/l48 E 3,490,426 l/l970 Farr ....l23/l48 E X 3,524,4388/1970 Janisch ..l23/l48 E Primary Examiner-Laurence M. GoodridgeAttorney-D. Henry Stoltenberg [5 7] ABSTRACT A dynamoelectric generatingdevice for internal combustion engines combining a breakerless ignitionsystem of a condenser discharge type with an alternator for generatingelectrical power wherein the energizing and timing coils for theignition system are mounted on a stator with the power generating coils,both being excited by a rotating permanent magnet structure driven bythe engine. An automatic spark advance is provided actuated at apredetermined engine speed.

2 Claims, 4 Drawing Figures PATENTEUMARZB I972 3,651,795

sum 1 OF 2 INVEN'IOR.

RAY C. NODD l N ATTORNEY PATENTEUMRZEB I972 3,651,795

mam 2 OF 2 7\ CHARGE COIL 2a r f t START TRIGGER COIL 30 M 3 m k ,Md W-N TRIGGER COIL 32 INVENTOR.

RAY C. NODD! N ATTORNEY MAGNE'IO EXCITED CONDENSER DISCHARGE IGNITIONSYSTEM The combining of a breakerless ignition system of the condenserdischarge type using solid state components with a power alternator forpower circuits in a vehicle has long been sought as a suitable goal forcommercial exploitation. The present invention provides such acombination in a form wherein a recovery period for the solid statecomponents of the ignition circuit is attained with low cost andreliability. An automatic advance for ignition timing at a predeterminedspeed of the engine is also attained without complicated structuresbeing used.

It is therefore a principal object of this invention to provide I abreaker-less ignition system of the condenser discharge type combinedwith a power alternator wherein a high efficiency and reliability ofboth elements is attained.

It is a further object of this invention to provide a breakerlessignition system of the condenser discharge type energized and triggeredby a magneto, which utilizes solid state components and which has anautomatic spark advance at a predetermined speed of rotation of theengine.

Other objects and advantages of this invention relating to thearrangement, operation and function of the related elements of thestructure, to various details of construction, to combinations of partsand to economics of manufacture will be apparent to those skilled in theart upon consideration of the following description and appended claims,reference being had to the accompanying drawings forming a part of thisspecification wherein like reference characters designate correspondingparts in the several views.

FIG. 1 is a top plan view of an alternator to which the invention hasbeen applied;

FIG. 2 is a bottom plan view of the same;

FIG. 3 is a schematic diagram of connections of the ignition system; and

FIG. 4 is a graph showing the timing relations of the generated pulsesof the coils cooperating with the ignition circuit.

Referring to the drawings particularly to FIG. 1, a fixed circularstator element is shown which is attached to an engine (not shown) bybolts 22. The engine may be single cylinder, two cycle type, or may beof the multi-c'ylinder type used in connection with various devices suchas boats, tractors and the like. The engine is provided with a rotatabledrive shaft 24 concentric with the stator 20, being provided withsuitable bearings in the conventional manner.

The stator 20 is provided with outwardly projecting poles 26 which arespaced in equidistant relation about its outer circumference. In thesystem shown, 12 poles are provided, although more or less may beutilized in design variations. The ends 26a of the poles are curved andconcentric with the shaft 24. As is conventional, the stator islaminated to reduce losses due to eddy currents.

For convenience in description, the poles have been numbered 1-12, beingspaced 30 apart about the circumference of the stator as shown inFIG. 1. Pole No. 1 has mounted on it a charging coil 28, while pole No.2 is open without any coil being mounted thereon. Pole No. 3 has twotrigger coils 30 and 32 mounted on it, the trigger coil 30 being usedfor starting, while the trigger coil 32 is used for normal runningconditions for the engine. All three coils 28, 30 and 32 are used withthe ignition circuits for the engine as will be further describedhereinafter.

On poles Nos. 4-12, power coils 34 are mounted, which are connected inseries to form an alternator of the conventional type which, whenconnected to the power circuits of the vehicle or the like on which theengine is mounted, may be used to charge batteries, operate lights etc.These circuits are well known and will not be described further. All ofthe coils mounted on poles Nos. 1-12 may be prewound on bobbins orotherwise and carefully insulated electrically from the stator member 20as is conventional and well known in the art.

Exteriorly of the pole surfaces 260, a rotor 36 is provided whichcooperates by means of minimal air gap 38 with the poles ends to providemagnetic excitation of varying density to generate proportionatevoltages in the various coils. For this purpose a rotor structure isprovided which mounts up to give equally spaced magnet groups 40, withat least one magnet group being omitted and replaced with suitablecounterweights 42 having no magnetic properties so that a balanced rotoris attained to be suitable for rotation at high speeds. The rotor 36 issuitably mounted in a conventional manner on the shaft 24 to rotatetherewith so that the magnet groups 40 are driven past the stator polesNos. l-12 to magnetically excite the coils with a period of recoverywhen no magnetic excitation occurs by the passage of the non-magneticcounterweights 42 as will be described further hereinafter.

The lower side of the rotor is provided with flutes 36a, as seen in FIG.2, which during rotation cause a flow of cooling air to pass through thestator 20 for reducing the operating temperatures under load. The magnetgroups 40 consist of high coercive permanent magnets 40a cooperatingwith laminated magnetic shoes 40b at each end of the magnets 40a toprovide magnetic north and south poles in closely juxtaposed relation inthe air gap 38 to provide the magnetic excitation. All of the members ofthe rotor are held in fixed relation by the rotor structure. The poleshoes 40b extend into the inner circular opening 40c of the rotorconcentric with the shaft 24 and also concentric with the outer endsurfaces 26a of the poles 26 numbered l-12 on the stator 20.

Referring now to FIG. 3 which is a schematic diagram of connections ofthe magneto when used in connection with a condenser discharge ignitioncircuit for a single cylinder engine, a charging condenser C, is shownin circuit with the primary P of a step-up transformer SP whosesecondary S is connected to a spark gap or spark plug G to fire theexplosive charge in the cylinder of the engine (not shown). One side ofthe condenser C, is connected to ground GR, while the op posite side isconnected to the primary P through which the condenser C, may be chargedby charging coil 28 acting through resistance R, and R and diodes D, andD An SCR is connected across the condenser C, and the primary P, beingnormally non-conductive to allow charging of the condenser C, by thecoil 28. When however, a suitable positive potential is applied to thegate electrode of the SCR, it becomes conductive and allows the chargedcondenser C, to discharge through the primary P of the step-uptransformer SP to induce a high voltage in the secondary S which firesthe spark plug G and ignites the combustible charge in the cylinder ofthe engine. The charging coil 28 is grounded through resistance R tocomplete the charging circuit for the condenser C,.

In order to apply the suitable positive voltage pulse to the gateelectrode of the SCR, trigger coils 30 and 32 (See FIG. I & 3) areprovided, which are both connected to the gate electrode of the SCR andboth have one side grounded as shown. The start trigger coil 30 hasapproximately five times the number of turns found in the run triggercoil 32, so that at low speeds of rotation of the rotor 36, the voltagesgenerated in the two coils will be proportional and so designed thatuntil a predetermined speed of rotation of the rotor 36 is reached, thevoltage generated in the run trigger coil 32 is below (position 2-3 inFIG. 4) that voltage required to fire the SCR, while that generated inthe start" trigger coil 30 would be sufficiently high to fire the SCRbut is not of the right polarity being negative rather than positive asrequired to fire SCR. This is clearly shown in FIG. 4. The firingvoltage F for the SCR is shown in dotted line as a positive potential inthe graphs for the start" and run trigger coils. At the 1-2 positionwith the leading magnet group 40A having just passed the charge coil 28on pole No. 1 in FIG. 1, the positive charge pulse A has been stored onthe condenser C, as pointed out above which is now ready to energize theprimary P of the step-up transformer SP before pole No. 1. The negativepulse N in the start" trigger coil 30 is of the wrong polarity while thepositive pulse B in the run" trigger coil 32 is too low to reach therequired triggering voltage F for the SCR with the result that the SCRdoes not fire and no spark occurs at the spark plug G.

Then, as the leading magnet group 40A in FIG. 1 approaches the 3-4position by advancing another 30 mechanical degrees (equivalent to 180electrical degrees) a positive pulse Q occurs in the start trigger coil30 which is sufficiently high in voltage to fire the SCR which thenbecomes conductive and discharges the condenser C through the primary Pto induce a high voltage in the secondary which causes an ignition sparkat the spark plug G. The pulse W generated simultaneously in the runtrigger coil 32 is negative and therefore of the wrong polarity to firethe SCR.

As the speed of rotation of the rotor 36 increases, and approaches apredetermined speed, the voltage amplitude of the pulse B in the "runtrigger coil 32 increases until the voltage of the pulse B is sufficientto fire the SCR, which occurs approximately 30 earlier, therebyadvancing the spark at the spark plug G by this amount. This occurs atstation 2-3 of the stator 20 which is the normal timing of the spark atthe spark plug G for normal operation of the engine. Following thisinitial spark, the SCR will be held in conductive condition until 8-9station is reached by the leading magnet group 40A, inasmuch astriggering pulses have been applied to the gate electrode of the SCR byboth the start" and run" trigger coils 30 and 32 as is shown in FIG. 4.The charging pulses of the charging coil 28 are short-circuited by theconductive condition of the SCR, which pulses terminate at position 7-8and none again occur until the new 1-2 position is reached by theleading magnet group 40A. This is due to the absence of any magneticexcitation by the non-magnetic counterweight 42 which spans at least 60mechanical degrees of the rotor 36. This nonexcitation for at least 60of the rotor also affects the trigger coils 30 and 32 as is clearlyshown in FIG. 4, where no pulse of any kind is generated in position11-12 which is a recovery period for the ignition circuit, allowing allelements to become inactive, particularly the SCR which is returnednon-conductive nonconductive state. This is assured by the resistor R inconjunction with diode D and resistor R which provide a negative bias onthe SCR prior to a new charge cycle. The diode D which is a zener,prevents small charge pulses from charging the condenser C which whendischarged could cause maverick sparking. Resistor R regulates thecharging voltage to the condenser C keeping it constant during normaloperation, particularly when used with diode D The combination obviatesthe need of a loading power zener diode.

The ignition circuit disclosed when operated as described, provides onespark per revolution, but with some modifications and selecting suitablelocations of the exciting magnets and additional trigger coils, two ormore sparks per revolution may be obtained. It is important that atleast one recovery period be provided during a revolution in which nopulses are generated, either in the charging coil or in the triggercoils. Immediately following the recovery period, a new cycle will beginby charging the condenser C, with a new charging pulse by the coil 28all as described above.

The run" trigger coil 32 is connected to the gate electrode of the SCRthrough variable resistance R and resistance R, with a third ResistanceR being connected to the junction of the first two resistances. Anegative temperature resistor R, connects the other side of the resistorR to ground, which gives an operator temperature compensation controlover the firing times of the SCR by adjusting the variable resistance RThe resistors R R and R form a voltage divider for controlling thevoltage applied to the gate electrode of the SCR. By decreasing orincreasing the value of the variable resistance R the voltage appliedfrom the "run" trigger coil 32 to the gate electrode of the SCR may beincreased or decreased, respectively. Hence, varying the value of theresistor R varies the speed of the engine at which a sufficient voltageis applied from the run" trigger coil 32 to the gate electrode of theSCR for triggering the SCR. The resistor R is a thermistor having anegative temperature coefficient. When the engine is heated duringoperation of the engine, the resistance of R decreases to decrease thevoltage applied from the run trigger coil 32 to the gate electrode ofthe SCR. The trigger coils 30 and 32 are both connected to the gateelectrode of the S CR, generally in arallel with each other.

The following parameters or the ignition circuit shown in FIG. 3 havebeen found successful:

5500 turns No. 40 wire I500 turns No. 35 wire 300 turns No. 35 wire 0.68microfarnds Charging coil 28 Start trigger coil 30 Run trigger coil 32Condenser C It is understood that the above detailed description of thepresent invention is intended to disclose an embodiment thereof to thoseskilled in the art, but that the invention is not to be construed aslimited in its application to the details of construction andarrangement of parts illustrated in the accompanying drawings since theinvention is capable of being practiced and carried out in various wayswithout departing from the spirit of the invention. The language used inthe specification relating to the operation and function of the elementsof the invention is employed for purposes of description and not oflimitation, and it is not intended to limit the scope of the followingclaims beyond the requirements of the prior art.

I claim:

1. Electrical power producing apparatus for operating an internalcombustion engine comprising, in combination, a stepup transformer forgenerating a high voltage for producing timed ignition sparks, acapacitor, electronic switch means having input, output and controlterminals, means connecting said capacitor, the primary winding of saidtransformer and said input and output terminals of said switching meansin a closed series circuit whereby said switching means when energizeddischarges energy stored in said capacitor through the primary windingof said transformer, an alternator including a stator having a pluralityof spaced poles and a rotor having unequally spaced permanent magnetgroups, means for rotating said rotor in synchronism with the engine,said magnet groups being located on said rotor to form changing magneticcircuits with said pole pieces as said rotor is rotated, said alternatorhaving at least four windings for producing first, second, third andfourth voltages, means mounting said first winding on a first of saidpoles for periodically inducing a first voltage across said firstwinding, means for charging said capacitor with said first voltage,means mounting said second and third windings on a second of said polesfor periodically generating alternating voltages out of phase with eachother, means spacing said second pole from said first pole whereby saidcapacitor is charged prior to inducing voltages across said second andthird windings, means mounting said fourth winding on at least one ofthe remaining poles for producing power for a power consuming circuit inthe engine, and means applying at least a portion of the alternatingvoltages from said second and third windings to said control terminalfor energizing said switch means during half cycles of one polarity whenthe voltage exceeds a predetermined level, said second windingperiodically producing a first voltage of said one polarity exceedingsaid predetermined level when said rotor is rotated and said thirdwinding periodically producing a second voltage of said one polarityadvanced in phase from said first voltage and exceeding saidpredetennined level only when said rotor is rotated faster than apredetermined speed.

2. The apparatus of claim 1 which further includes means for selectivelyvarying the predetermined speed at which said third winding will producea voltage exceeding said predetermined level.

[01029 Old]

1. Electrical power producing apparatus for operating an internalcombustion engine comprising, in combination, a step-up transformer forgenerating a high voltage for producing timed ignition sparks, acapacitor, electronic switch means having input, output and controlterminals, means connecting said capacitor, the primary winding of saidtransformer and said input and output terminals of said switching meansin a closed series circuit whereby said switching means when energizeddischarges energy stored in said capacitor through the primary windingof said transformer, an alternator including a stator having a pluralityof spaced poles and a rotor having unequally spaced permanent magnetgroups, means for rotating said rotor in synchronism with the engine,said magnet groups being located on said rotor to form changing magneticcircuits with said pole pieces as said rotor is rotated, said alternatorhaving at least four windings for producing first, second, third andfourth voltages, means mounting said first winding on a first of saidpoles for periodically inducing a first voltage across said firstwinding, means for charging said capacitor with said first voltage,means mounting said second and third windings on a second of said polesfor periodically generating alternating voltages out of phase with eachother, means spacing said second pole from said first pole whereby saidcapacitor is charged prior to inducing voltages across said second andthird windings, means mounting said fourth winding on at least one ofthe remaining poles for producing power for a power consuming circuit inthe engine, and means applying at least a portion of the alternatingvoltages from said second and third windings to said control terminalfor energizing said switch means during half cycles of one polarity whenthe voltage exceeds a predetermined level, said second windingperiodically producing a first voltage of said one polarity exceedingsaid predetermined level when said rotor is rotated and said thirdwinding periodically producing a second voltage of said one polarityadvanced in phase from said first voltage and exceeding saidpredetermined level only when said rotor is rotated faster than apredetermined speed.
 2. The apparatus of claim 1 which further includesmeans for selectively varying the predetermined speed at which saidthird winding will produce a voltage exceeding said predetermined level.